In a test for metastasis of cancer, it has been carried out to administer radioactive medicine into a body and detect radioactive material agglomerated in the tissue of the body, thereby specifying the position of the tissue to which the cancer metastasizes. An example of a radiation detector used to detect radioactive material is described in U.S. Pat. No. 6,236,880 B1. This radiation detector is of a hand held type. In this radiation detector, a curved tube is connected to the distal end of the main body, and various probe distal ends can be mounted on the distal end of the tube. A radiation detection element is built into each probe distal end.
In the field of the radiation detector, a radiation detector which is easier to handle has been required to quickly detect radioactive material in a body.